Hard to guess what it will be, but I'm thinking based on WG track record:
1. British heavies
2. Some new premium (the !atilda BP was just announced so maybe the 8.8 in the tech tree?)
3. A new map
Though there will be a claim for bug fixes, they sure seem to come slow. However, I HOPE that we will get:
1. A fix for the family sharing bug (only three months old now)
2. Graphics optimization and an option for A7 powered iOS devices to switch back to the older lower resolution like the A6 iOS devices and older
3. Fix the 8.8 overlay when targeting
4. Fix the Winter Malinovka issue where shots hit the ground when you're only 200 meters away
5. Clan wars or preparations for them (like training rooms)
6. Give back the German Mediums their top engines (I don't even drive that line)
7. Fix the friend's list and chat issues (why is advancing censored?)
8. Limit gold ammo to a percentage of total capacity (maybe 40-50% seems reasonable)
9. Achieve better BALANCE of tiers between sides (if we have one less ten, make it up an with an extra nine, not two eights)...I know this one is rather contentious with some on the forums, LOL
10. Real similar to no. 9 but allow players the option to wait longer in queue to minimize tier differences. (Even if only in tiers 8-10; wouldn't it be glorious to see no eights in a tier ten match, or vice versa).
Zac